1. Field of the Invention
The present invention relates generally to a bicycle clamping stem which is a structure for fastening a bicycle handlebar to a bicycle fork steering tube of the bicycle front frame.
2. Description of the Prior Art
A bicycle front frame of the prior art utilizes a clamping structure for fastening a bicycle fork steering tube and a handlebar of the bicycle. The prior art clamping stem structure is provided at two ends with a plurality of fastening holes by which the front fork steering tube and a handlebar of a bicycle are respectively fastened together with the clamping structure. In the most commercially popular handlebar clamping stems a generally block-shaped structure is formed having a pair of rearwardly extending arms that define a generally cylindrical, nearly vertical opening therebetween. The distal extremities of the arms have a slight degree of resiliency and are drawn together by a pair of bolts.
In the forward portion of the structure a transverse, generally horizontal, semicylindrical groove is formed. A front end cap has a corresponding semicylindrical groove in its rear side and is attached to the forward portion of the block-shaped structure by four bolts. The clamping stem can thereby be attached by inserting the fork steering tube through the generally vertical, cylindrical opening formed in the clamping stem and tightening the bolts at the distal, rearward extremities of the arms. The front end cap is removed so that the center of the handlebar structure is seated in the transverse, semicylindrical groove formed in the front face of the clamping stem block. The front end cap is then attached to the front end face of the clamping stem block by bolts that are tightened to rigidly secure the handlebar in position.
In such conventional clamping stem structures it is not possible to concurrently secure the steering tube and the handlebars at the same time. Such prior structures are therefore inefficient at best, and are not cost-effective.
Another prior clamping stem system is commercially available and is sold as the Bizhouse Dializer model No. 26-370019. This clamping stem arrangement is formed of three configured component pieces, the central one of which is shaped to form a surface of contact for the fork steering tube on one side and a surface of contact for the handlebar on the other side. Four clamping bolts are utilized to tighten the three configured component pieces toward each other to concurrently clamp the handlebar and the fork steering tube at the same time. However, like the other conventional prior art devices, it is necessary to tighten four different bolts separately in order to clamp the component parts together.